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Tramping Geology through the Appalachians. Original music by Bob Blackshear: Nashville recording artist Song writer and singer Sun City Resident. Vagabonds & Sojourners Tramping Geology: The Appalachian Mountains. Session 1: Getting Started.
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Tramping Geology through the Appalachians Original music by Bob Blackshear: Nashville recording artist Song writer and singer Sun City Resident
Vagabonds & Sojourners Tramping Geology: The Appalachian Mountains Session 1: Getting Started An Overview of the Next 6 Weeks Remember our field trip, Nov. 3rd
Geology in the News Next, diamonds reveal geology of the deep “earth furnace” that generates many of our natural metallic resources New York Times, Sept.15, 2011
Geology in the News Continent Oceanic crust And, China turns out our “green” lights, at least for a while New York Times, Sept.16, 2011 Mantle plume (hot spot)
Geology in the News Now to “playing in the sand pile” in McCulloch County, Texas Austin American statesman, 9-18-11 New York Times, Sept.16, 2011
McCullough County Austin Up close
McCullough County Sand quarries
500 million year old sandstones McCulloch County The big picture: why sand here? Is the favorable sand elsewhere?
North America 505 million years ago Ancient beach sands McCullough County Now to an earthquake in Himalayas
Geology in the News Tibet-China 6.9 India
Geology in the News Nile geosyncline gas prone
Cyprus Offshore territory Nile geosyncline gas prone Back to the Western Hemisphere
Expensive production from deep water (6,000 feet+) Brazil and Canadian tar sands forecast to provide oil to replace diminishing resources in Mexico and Venezuela.
Geology in the News Computer modeling of oil & gas reservoirs using seismic, drilling, production, and conceptual data Now, back to the Appalachians
Vagabonds & Sojourners in the Appalachians Six Sessions As we follow the Great Valley we’ll: 1. explore the heart of the Appalachians 2. note to economic resources of the interior 3. relate human history to the last great continental glacier Return to NC & follow the Great Valley through VA, WV, MD, PA, NY, CT, & VT into Canada Where are the lands of the Sojourners? Begin in North Carolina Blue Ridge Mts Follow the Blue Ridge to Georgia & Alabama
The Lands of the Sojourners 5 1 17 3 14 0 1 The Appalachian Geologic Province 4 14 Sandi’s first geology field trip: Wisconsin Dells age 6 months 4 2 Back to Session 1 11 7 5
Vagabonds & Sojourners Tramping Geology: The Appalachian Mountains Session 1: Getting Started What is a geologic mountain?
What is a geologic mountain? Rocks deformed by the collision of two plates of the earth’s crust Mountains grow to great heights & are gradually destroyed by weathering & erosion Mountain Classification
Mature Mountains: Mount Mitchell, North Carolina
Old Age Mountains: Granville Range Llano County, Texas
What is a geologic mountain? Rocks deformed by the collision of two plates of the earth’s crust Mountains grow to great heights & are gradually destroyed by weathering & erosion Mountains are composed of folded, faulted, and melted rocks
Folds, faults, and melted rocks Blue Ridge Mountains Coastal Plain Piedmont Great Valley Valley & Ridge Appalachian Geologic Province Folded & faulted rock layers Melted rock masses Partially melted rock mass
What is a geologic mountain? Rocks deformed by the collision of two plates of the earth’s crust Mountains grow to great heights & are gradually destroyed by weathering & erosion Mountains are composed of folded, faulted, and melted rocks Mountain building exposes different rock types at the surface
Folds, faults, and melted rocks Blue Ridge Mountains Coastal Plain Piedmont Great Valley Valley & Ridge Folded & faulted rock layers Melted rock masses Partially melted rock mass What type of rocks do we have in the Valley & Ridge Province?
A Land of Long Ridges and Valleys What made the ridges & valleys? Sedimentary rocks of all kinds
What made the valleys & ridges? Dense white limey rock made low ridges Sandstones, Limestones, & Shales: rocks of the Valley & Ridge Province A gray soft rock made these low hills A black mud stone made this stream valley A yellow sandy rock made prominent ridges rocks made from sediments deposited in the oceans along continental margins
Sediments Rocks Sediments accumulate in oceans at continental margins They accumulate in layers, one on top of another They are composed of: sand, mud, &/or sea shells How do these sediments become rocks?
Creating the Three Sedimentary Rock Types Limestones: made from sea shells Sandstones: made from “ beach” sands Shales: made from mud and silt A Simple Example
Cross Section showing different Sediment layers Shell layer Mud layer Sand layer How do these soft sediments become solid rocks? Let’s follow one shell layer as it becomes a limestone
How are Solid Rocks Formed? Example: Limestones in Williamson County Edwards started out as a “shell” layer 400 feet thick What happened next?
Layer after layer of sediment deposited on top of Edwards “shell” layer Burial, compaction and dewatering.
Many more layers of sediment deposited on top of Edwards Edwards shells recrystalize to limestone with fossils What happens to newly formed rocks? Continued burial to depths as deep as 10,000 feet and deeper
What did we find east of the Valley & Ridge Province? Uplift brings to the surface natural resources created at great depth: e.g. metals, coal, oil, etc Deeply buried Edwards Limestone layer Uplifted, Weathered, and Eroded
Valley and Ridge province Great Smoky and Blue Ridge mountains What type of rocks do we find in these mountains?
The Blue Ridge Mountains What type of rocks do we find in the Blue Ridge Mountains? Metamorphic Rocks: sedimentary rocks buried to great depth, squeezed , crushed, & partially melted Parallel to & east of the Blue Ridge is the Piedmont geological province Origin of metamorphic rock types: sandstone = quartzite limestone = marble shale = slate sandstone + shale = schist = gneiss** ** most common metamorphic rocks rocks of the Blue Ridge Mountains
Geologic Provinces of North Carolina Great Smoky Mountains 600 million year old sandstones & shales Blue Ridge mountains 300 million year old metamorphic rocks Piedmont hills 300 million year old metamorphic & igneous rocks Coastal Plain 1 to 65 million year old sand & clay Offshore Continental Shelf Recent sand & clay The Piedmont geologic province Igneous & metamorphic rocks What is an igneous rock?
What is an igneous rock? Remember that Metamorphic Rocks are: sedimentary rocks buried to great depth, squeezed , crushed, & partially melted Origin of metamorphic rocks: sandstone = quartzite shale = slate limestone = marble granite basalt An igneous rock one formed by complete melting & cooling of a pre-existing rock Where do we find igneous rocks? Let’s look at the big picture Two principle igneous rocks: granites-rhyolites & basalts-gabbros
The Solid Earth Rocky Crust Plastic Rocky Upper Mantle Focus on the rocky crust
The Earth’s Rocky Crust: Two Types Oceanic Crust: 5 miles thick under the oceans: basalt Continental Crust: 20 to 50 miles thick makes the continents: granite Let’s look at the Oceanic Crust The Mantle: “Molten” (plastic) rock below the crusts
The Earth’s Oceanic CrustThe Rocky top of the Mantle Oceanic Crust: basalt 5 miles thick Ocean The Earth’s Mantle plastic (molten) rocks A world view
Oceanic Crust: dark colored rocks dense rocky top of the mantle: basalt Oceanic Crust: dark colored rocks dense rocky top of the mantle All the dark blue are basalt All the dark blue are basalt Next the Continental Crust
The Earth’s Continental Crust“Floating” on the Mantle Oceanic Crust Continental Crust The Earth’s Mantle A world view
Continental Crust: light colored rocks less dense than oceanic crust “floats” on the mantle: granite How “thick” is North America compared to the whole earth?
Our Earth Radius = 4000 miles Interior of Our Earth